Numerical Simulation of Geosynthetic-Reinforced Flexible Pavements

Abstract

In traditional analyses of flexible pavements the linear elastic material behavior is assumed for pavement materials. However, pavement materials do not behave as linear elastic materials. They can be better modeled by using elasto-plastic constitutive relationships. The consequences of the assumption of linear elasticity in the prediction of the behavior of geosynthetic-reinforced flexible pavements are presented. The effect of the stiffness of geosynthetic reinforcements on pavement behavior is also studied. The behavior of a geosynthetic-reinforced flexible pavement is analyzed by the finite-element method with different constitutive models. The results of six analyses where E is Young's modulus [Case 1, linear elastic models with geosynthetics (Case 1a, E = 1 GPa; Case 1b, E = 100 GPa); Case 2, linear elastic models without geosynthetics; Case 3, elasto-plastic models with geosynthetics (Case 3a, E = 1 GPa; Case 3b, E = 100 GPa); and Case 4, elasto-plastic models without geosynthetics on the same pavement under the same load cycle] are presented and compared. Key observations and conclusions are as follows. The linear elastic analyses predicted tensile stresses in the crushed limestone layer although in reality this material cannot withstand tensile stresses. The vertical stresses directly under the load for all of the analyses were very close and were little smaller than those predicted by Boussinesq's equations. The linear elastic analyses showed only a small reduction in settlements when geosynthetics were added. In contrast, elasto-plastic analyses showed a large reduction in settlements, especially with stiffer geosynthetics. Previously published field data indicate an improvement in the pavement performance when geosynthetic reinforcements are introduced.